Automatic stoker



J. P. NORTON 2,003,385

AUTOMATIC STOKER Filed 061;. 21, 1931 June 4, 1935.

-|NVENTQR JAMES P NOR TON ATTRNEY g Patented June 4, 1935 UNITED STATESPATENT OFFICE AUTOMATIC STOKER Application October 21, 1931, Serial No.570,164

Claims.

This invention relates to automatic stokers, and more particularly tostokers of the underfeed type in which reciprocable rams mounted in ramcasings are utilized to force the fuel into the 5 furnace.

The rams of these underfeed stokers are frequently driven by means of acrank shaft and connecting rods, the connecting rods being pivotallyjoined to the rams by wrist pins. In some cases the wrist pins extendthrough slots in the sides of the ram casings, and serve to drivesecondary fuel feeding members, such as pusher blocks or reciprocableretort sides. With such a construction, a ram cannot be removed forrepair or replacement without first withdrawing the corresponding wristpin, and this is ordinarily prevented by the proximity of the adjacentram casing. In order to avoid this difficulty, it has been customary toform each wrist pin of two parts which can be separately inserted orremoved. This construction is not only structurally weak, but itprovides an insufiicient bearing area for the connecting rod.

It is accordingly the main object of the invention to provide anautomatic stoker in which each of the wrist pins which join theconnecting rods to the reciprocable rams may be formed in one piece andyet may be readily removed when desired without interference with theadjacent ram casing.

It is a further object of the invention to provide a construction forthe wrist pins and their associated parts which will be structurallystrong and capable of operating under severe service conditions for along period without attention, and which will provide ample bearing areaand thereby reduce wear to a minimum.

It is a further object of the invention to provide a simple, inexpensiveand easily assembled construction including a frangible member whichwill yield and allow the crank shaft to continue its rotation withoutdamage to any of the parts in case the ram becomes blocked by anobstruction.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

Referring to the drawing illustrating one embodiment of the invention,and in which like reference numerals indicate like parts,

Fig. 1 is a section through a portion of an automatic stoker, thesection being taken on the line ll of Fig. 3;

Fig. 2 is a section on the line 2-2 of Fig. 3;

Fig. 3 is a section on the line 3-3 of Fig. 1; and

Fig. 4 is a section on the line 4-4 of Fig. 1.

In the drawing I have shown a portion of a multiple retort underfeedstoker of the general type disclosed in the prior patent to Riley No.1,090,651. The illustrated embodiment comprises a series of hollowcylindrical ram casings l0 extending forwardly from the front wall II ofa furnace, with their axes parallel and in the same horizontal plane.These ram casings are spaced rather closely together, as is necessary instokers of this type, to match the spacing of the retorts (not shown)within the furnace. An opening 12 is provided through the wall ll at therear end of each ram casing for the delivery of fuel to the retorts. Anopening or throat I4 is formed in the upper wall of each ram casing nearthe furnace wall H, and a fuel hopper I5 is mounted above each throat.The ram casings ID are held in the desired relative positions bysuitable tie members, shown as angle irons I1, l8 and I9 extendinghorizontally and parallel to the wall I l.

Slidably mounted within each ram casing is a reciprocable fuel feedingram 21 shaped as a hollow cylinder closed at its rear end and open atits front end. The rams 2i are'arranged to be reciprocated by means of acrank shaft 22 mounted in front of the ram casings and rotatable about ahorizontal axis. Each ram is joined to the crank shaft by a connectingrod 23. The crank shaft is arranged to be driven by a speed reducingmechanism 25 to which any suitable source of power may be applied.

On the rear end of each connecting rod 23 I provide a bearing member 2'!shaped as a hollow cylinder. A horizontal cylindrical wrist pin 28extends through each bearing member and is supported in bosses 29 formedon the inside of the ram. Set screws 30 (Fig. 4) hold the wrist pin inplace. It will be noted that this construction forms a strong pivotalconnection between each connecting rod and its corresponding ram, andthat ample bearing area is provided- The wrist pins 28 are preferablyarranged to drive secondary fuel feeding members, such as reciprocableretort side walls as shown in the patent to Riley No. 1,090,651, and forthis purpose the ends of the wrist pins are extended through horizontalslots 32 in the sides of the ram casings. These ends are shown somewhatsmaller in diameter than the main body of the wrist pin. At each side ofeach ram casing is a horizontal cylindrical rod 33 (Fig. 2), which isslidable axially through a boss 34 integralwith the ram casing.

It will be understood that each rod 33 may be connected at its rear endto a reciprocable retort side wall (not shown). A bolt 36 forms aforward extension of each rod 33, and these bolts 36 pass throughopenings or slots 31 in the ends of the wrist pins. A nut 38 (Fig. 2)threaded on each bolt provides an adjustable abutment for the wrist pinto strike on its rearward movement. On the forward stroke the wrist pincontacts with the-heads 39 of the bolts. This construction provides anadjustable lost motion driving connection substantially identical withthat disclosed in the above-mentioned patent to Riley.

It will now be seen from Fig. 3 that the wrist pins 28 are too long tobe withdrawn in the horizontal axial direction, since they wouldinterfere with other parts and particularly with the adjacent ramcasing. The ram casings are carefully aligned and firmly fastened inposition, and their removal is a diflicult and laborious task whichshould not be undertaken unless absolutely necessary. It will also beclear that the rams cannot be removed from the ram casings without firstwithdrawing the wrist pins.

In order to overcome this difliculty I have provided enlarged openings4i in the side walls of the ram casings. These openings 4i arepreferably located at the front ends of the slots 32, and theirdimensions are such that the ram may be turned about its axis and thewrist pin then withdrawn longitudinally without interference with theadjacent ram casing, as indicated by the dot and dash lines in Fig. 3.Ordinarily a section of the crank shaft 22 will need to be removed, toallow complete withdrawal of the ram from the ram casing. It will besumcient from an operative viewpoint if the openings 4| extend onlybelow the horizontal plane at one side of the ram casing and only abovethe horizontal plane at the other side. However, I prefer to form bothsides of the ram casing in the, same way, to provide a symmetricalconstruction. The openings 4| in the drawing therefore extend both aboveand below the horizontal plane.

In the operation of a stoker of this type. one of the rams 2| may becomeblocked by a foreign body, and it is desirable to provide a frangiblemember which will yield under these conditions and prevent damage to thedriving mechanism. For this purpose I provide a collar 44 which fitsloosely upon the outside of the connecting rod and which is normallyheld in a fixed position thereon by a horizontal shear pin 45 extendingthrough both these parts. The collar 44 normally contacts with the frontsurface of the bearing member 21 and transmits thereto the force exertedby the connecting rod on the rearward stroke.

1 If this force for any reason'becomes excessive,

the pin 45 will shear and allow the connecting rod to slide through thecollar 44 and the member 21.

In order that the connecting rod may slide in this manner, the wrist pin28 is formed with an opening 41 extending transversely through itscenter in a horizontal direction, and the bearing member 21 is providedwith an opening 48 in direct alignment with the connecting rod. Theopening 41 is enlarged at each end in a vertical direction to allow forthe angular movement of the connecting rod in a vertical plane, onlyenough material being removed to avoid interference.

The collar 44 and shear pin 45 are effective during the fuel feedingstroke only, and additional means must be provided to move the ramforwardly. For this purpose I provide a groove 50 extendinglongitudinally along the outer surface of the connecting rod, and ascrew BI is threaded through the front portion of the bearing member 21with its end located in this groove. In normal operation the screw ii ispositioned at the rear end of the groove, which forms an abutment incontact with the screw and thus prevents the connecting rod from slidingforwardly relative to the bearing member. I preferably provide two ofthese screws SI and two grooves 50, one on the top of the connecting rodand one beneath. It will be clear that the grooves 50, as well as thebolts 36, normally prevent the ram from turning about its axis, and thedesired alignment of the wrist pin bearing is therefore maintained.

The operation of the invention will now be clear from the abovedisclosure. The' crank shaft 22 is rotated by means of a suitable sourceof power connected to the speed reducing mechanism 25, and the rams 3|reciprocate in the ram casings Ill, delivering fuel from the hoppers llthrough the openings i2 into the furnace. The wrist pins 28 reciprocatethe rods 33 at a reduced stroke because of the lost motion. If a ram onits rearward stroke encounters an obstruction which produces an abnormalstress on the connecting rod, the pin 45 will shear and allow theconnecting rod to slide through the bearing member 21. As the connectingrod moves forwardly, the shoulders at the rear ends of the grooves 53will contact with the screws ii and thus move the ram to its forwardposition, where it will remain until the obstruction is removed and anew shear pin inserted. Since each wrist pin is formed of a singlepiece, an increased bearing area is obtained, as well as a much strongerconstruction. A connecting rod can be removed at any time by firstdisconnecting it from the crank shaft and then removing the screws II,which are easily accessible when the ram is in its forward position. Awrist pin can be withdrawn by first removing the set screws 33 and thebolts 36, whereupon the ram may be turned about its axis and the wristpin slipped out longitudinally through the opening 4|, as indicated bythe dot and dash lines in Pig. 3. The entire construction is simple andinexpensive to manufacture and thoroughly dependable in operation, andthe various parts may be easily removed for replacement when necessary.

' Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. An automatic stoker comprising a ram casing, a hollow fuel feedingram reciprocable therein, a cylindrical wrist pin fixed within the ram,a. bearing member pivotally mounted on the wrist pin, a drivingconnecting rod slidable within the bearing member, the wrist pin havinga transverse opening therethrough through which the connecting rod maypass and the opening being enlarged at each end to allow for the angularmovement of the connecting rod, and frangible means normally preventingthe connecting rod from sliding relative to the bearing member.

2. An automatic stoker comprising a plurality of parallel ram casings,fuel feeding rams reciprocable therein, driving connecting rods, andwrist pins pivotally joining the connecting rods to the rams, the wristpin for each ram being formed in a single piece and extending throughopenings in the sides of the ram casings, and these openings being ofsufllcient size to allow the ramtobeturnedaboutitsaxisandthewrist pinwithdrawn longitudinally without interference with the adjacent ramcasing.

3. An automatic stoker comprising a plurality of parallel ram casingsmounted side by side and extending forwardly from the wall of a furnace,cylindrical rams reciprocable within the ram casings, driving connectingrods, horizontal wrist pins pivotally joining the connecting rods to therams, the ram casings having slots in each side and each wrist pin beingformed in a single piece with its ends extending through the slots, andmechanism arranged to be driven by the ends of the wrist pins, the slotshaving enlarged portions of suflicient size to allow the rams to beturned about their axes and the wrist pins to be withdrawnlongitudinally without interference with the adjacent ram casings.

4. An automatic stoker comprising a plurality of parallel ram casingsmounted side by side and extending forwardly from the wall of a furnace,cylindrical rams reciprocable within the ram casings, a crank shaftmounted in front of the ram casings and rotatable about a horizontalaxis, connecting rods actuated by the crank shaft, horizontal wrist pinspivotally joining the connecting rods to the rams, the ram casingshaving slots in each side and each wrist pin being formed in a singlepiece with its ends extending through the slots, and mechanism arrangedto be driven by the ends of the wrist pins, the slots having enlargedportions at their front ends of sufficient size to allow the rams to beturned about their axes and the wrist pins to be withdrawnlongitudinally without interference with the adjacent ram casings.

5. An automatic stoker comprising a ram casing, a hollow fuel feedingram reciprocable therein, a wrist pin formed in a single piece and fixedwithin the ram, a bearing member pivotally mounted on the wrist pin, adriving connecting rod slidable within the member, the wrist pin havinga transverse opening therethrough through which the connecting rod maypass, frangible means normally preventing the rod from sliding relativeto the member, the rod having a longitudinal groove therein whichprovides a shoulder at the rear endof the groove, and a screw mounted inthe bearing member and extending into the groove, the shoulder beingarranged to contact with the screw on the forward stroke and thus movethe ram to its forward position.

JAMES P. NORTON.

